/Engine/Source/Runtime/CoreUObject/Public/UObject/PackageResourceManager.h
Find the package in the package repository and set OutNormalizedPath equal to PackagePath, but with capitalization of the PackageName and LocalPath matching the capitalization present in the package repository's internal path string (e.g. the path on disk)
true if the package exists, else false
bool TryMatchCaseOnDisk ( const [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) & PackagePath, [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) * OutNormalizedPath )